In the alleys behind row homes in the Baltimore County neighborhood of Colgate, leaders of the local improvement association can see the telltale signs of the creatures they say have invaded their community.

Trash cans with no lids — the rats always find those. Garbage piled behind chain-link fences — feasts for the rodents. They've even made a home in what some call "Rat Mountain," a big mound of burrows in one front yard.

"Pretty much every household has been affected by it," said Dave Hyland, president of the Colgate Improvement Association.

The Dundalk neighborhood is part of County Council District 7, a waterfront area that is home to some of Baltimore County's most densely populated communities. The district features rowhomes, factories and piers along the Back River. It also has the county's biggest rat problem — by far.

No part of the county had half as many rodent complaints last year as the 807 filed in the area along the southeastern border of Baltimore City. Some residents say they're afraid of their own backyards because they're so overrun with rats.

The community has had to take things into their own hands. They report people who let their trash pile up. They distribute rat poison to neighbors.

"No citizen who pays taxes should have to live with rats," Hyland said.

Now the county plans to spend $150,000 annually over the next five years to treat its most infested areas. People whose neighborhoods are picked for treatment will be notified within a few weeks.

"Is this the rat police?" one woman called to Chen from her back steps. "There are more rats in this neighborhood than there are people!"

The woman, Miriam Lamkin, said she won't even go into her yard at night.

Two years ago, Baltimore County contracted with an exterminator to treat six communities in Dundalk, said Lionel Van Dommelen, head of code enforcement for the county. It helped for a while.

"The complaints are back on the rise, and folks just don't seem to understand that if they don't store their trash properly, that [the rats] are going continue to breed," he said.

The county will review complaint data to decide which neighborhoods will be treated in the eradication program, Van Dommelen said. They've already decided to treat Colgate, West Inverness, Berkshire, Riverview, Hawthorne, Norwood, Holabird and others. Residents will be able to opt out.

Some Colgate residents say they're frustrated with others who neglect their homes.

It used to be that "when you cut your grass, you sweep it up," said Cindy Kopicki, a former president of the improvement association.

"Not around here anymore," she said. "Now it lays in the street."

People who do take pride in their property can also suffer from rat infestations, Chen said. He pointed to one well-kept yard with several rat burrows by a shed.

"They can burrow easily," he said. "They love sheds, dog houses."

Eliminating food sources is the most important step in getting rid of rats, Van Dommelen said. People need to store their trash properly and clean up animal droppings.

"The amount of rodents cited in a neighborhood is directly correlated to the amount of garbage complaints," he said.

Rats are omnivorous creatures that eat a fair amount of animal protein, said Gregory Glass, a professor at the Johns Hopkins Bloomberg School of Public Health who studies microbiology and infectious diseases.

"They like things that have a lot of grease in them," he said.

Many rats die before they have a chance to breed, he said. In the Baltimore region, about half of rats are dead before they reach three months.

If they can access food, rats are more likely to survive until they're big enough to breed, he said. Most must weigh about seven ounces before they're sexually mature.

According to figures provided by the county, District 7 generated about half of the roughly 1,600 complaints the county got in 2011.

Councilman John Olszewski Sr., a Democrat who represents the area, said he has long advocated for more money for eradication, and helped secure the funds approved by the County Council last month. "I expect this to make a big improvement in our communities," he said.

Olszewski said residents need to do their part to keep neighborhoods clean, but that the county also has a responsibility.

But the problems stretched beyond the county's eastern edge. Complaints are also high in Riverview and pockets of Arbutus.

"I've been complaining for years," said Ron Whitehead, president of the Riverview Community Association. One neighbor reported that "rats had actually eaten into the asphalt in the parking area where she lives," he said. "It was terrible."

Code enforcement officials have cracked down on those who neglect their yards, and worked to educate communities to properly store trash, Chen said.

"We need the residents to help," Chen said."They are the key to this."

Hyland said inspectors do great work, but believes the county needs to devote more resources to fighting the rats.

"Code Enforcement has been busting their butts," he said. "[The county] should be budgeting for this on a regular basis until it's gone."

A burst of thunderstorm activity across the Chicago area in Sunday afternoon resulted in multiple injuries and a death at an event in west suburban Wood Dale, the collapse of a dome in northwest suburban Rosemont and the temporary evacuation of the music festival Lollapalooza in Grant Park downtown.

Now there are two: Zimbabwe accused a Pennsylvania doctor on Sunday of illegally killing a lion in April, adding to the outcry over a Minnesota dentist the African government wants to extradite for killing a well-known lion named Cecil in early July.